Lecture 22 Chapter 12 - Human-Computer Interaction

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Lecture 22Chapter 12 - Human-Computer
Interaction
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• A key design activity is to design the user
  interface
• Human-computer interaction (HCI) - the study of
  end users and their interaction with computers
• For every input and output the developer must
  consider the interaction between the user and the
  computer
• Because the interaction is much like a dialog
  between the user and the computer, user-interface
  design is often referred to as dialog design
• The field of human computer interaction
  investigates how people use computer systems, so
  that better systems can be designed
• One aspect is concerned with technological
  innovation (e.g. better input devices, like
  electronic pen etc.)
• The other aspect is concerned with the human
  element (e.g. how people reason, solve problems
  and interact with computers) the most
  challenging aspect of HCI!

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The User Interface

• Many people think of the user interface as a
  component added to the system near the end of the
  development process
• This view is changing as user interfaces become
  more important and systems become more
  interactive
• To the end user, the user interface is the system
• The user interface is everything the end user
  comes into contact with while using the system
  physically, perceptually, and conceptually
• Therefore, consideration of the user interface
  should come early in the development process

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Physical Aspects of the User Interface

• Physical aspects of the user interface include
  the devices the user actually touches, including
  the keyboard, mouse, touch screen, keypad
• Other physical parts include reference manuals,
  printed documents, data-entry forms, etc. that
  the end user works with completing tasks at a
  computer
• The desk space, the lighting, and the terminal
  hardware also make up the physical interface for
  the end user

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Perceptual Aspects of the User Interface

• Perceptual aspects of the user interface include
  everything the end user sees, hears, or touches
  (beyond the physical devices)
• This includes
• All the data and instructions displayed on the
  screen, including shapes, lines, numbers and
  words, sounds (like beeps etc.)
• Recently, computer-generated speech is another
  aspect
• The user touches objects such as menus, dialog
  boxes, and buttons on the screen using a mouse
• The user touches objects such as documents,
  drawings, or records of transactions

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Conceptual Aspects of the User Interface

• Conceptual aspects of the user interface include
  everything the user knows about using the system
  including the problem domain things in the
  system the user is manipulating, the operations
  that can be performed and the procedures followed
• To use the system, the end user must know all
  these details
• Users model (of the system)
• What the user knows about using the system,
  including the problem domainthings the user is
  manipulating, the operations that can be
  performed and the procedures followed when
  carrying out tasks

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• Designers model (of the system)
• How the designer sees and understands the system
• Problems with user interfaces can be considered
  as resulting from mismatches between the users
  model of the system and the designers model
• Leads to attempt to study how users view systems
  and how designers view systems can be a big
  gap!

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Users Model (continued)

• Much of the users model is a logical model of
  the system
• A logical model can be detailed so a user must
  know quite a few details to operate the system
• A users knowledge of the requirements for the
  system becomes the determinant of what the system
  is, and if the users knowledge of the system is
  part of the interface, then the user interface
  must be much more than something added at the end

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User-Centered Design

• A collection of techniques that place the user at
  the center of the development process
• Treat users as consultants in the design
  process
• Three important principles
• Focus early on the users and their work
• Evaluate designs to ensure usability
• Use iterative development
• Note that in user-centered design design and
  evaluation (testing of the design with end users)
  are considered together
• Iterate and evaluate until a satisfactory result
  is obtained (from the perspective of the end user)

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Notes on User-Centered Design

• The early focus on users and their work is
  consistent with the approach to systems analysis
  which emphasizes the importance of understanding
  and identifying the system users and their
  requirements
• In contrast, the traditional approach focuses
  more on the requirements from the business point
  of view what needs to be done from a processing
  perspective rather than a user perspective
• The object-oriented approach focuses more on
  users and their work
• With focus on use cases, actors, scenarios etc.
• Tend to be more interactive systems

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Notes on User-Centered Design (cont.)

• As discussed in ch. 7 the automation boundary
  between the user and computer is defined early
• User-centered design goes much further in
  attempting to understand users
• What do they know?
• How do they prefer to work?
• What motivates them?
• Very important questions when trying to add
  technology to complex areas, eg. Health care
  information systems

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Principles of User-Centered Design Continued

• Second principle of user-centered design
• To evaluate designs to ensure usability
• Usability refers to the degree to which a system
  is easy to learn and use
• Ensuring usability is not easy
• There are many different types of users with
  different preferences and skills to accommodate
  to
• If the system is too flexible, some users may
  feel lost
• If the system is too rigid some users will be
  frustrated
• Usability engineering
• Principled methods for ensuring usability
• Involves continual testing of prototypes with end
  users e.g. video analysis of end user
  interactions
• A very hot area currently

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Design and Evaluation Considered Together

• In past, traditionally considered as separate
  topics. In recent years it is becoming recognized
  that interactive systems require iterative design
• Promising approach for design of many systems
  (and user interfaces in particular)
• Iterate and evaluate until a satisfactory result
  is obtained
• Design principles can assist but do not help
  structure the process of design
• Need new design methodologies
• Rapid prototyping
• User-centered design
• Use of methods that go beyond to include
  continual usability testing with representative
  users doing representative tasks

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Usability continued

• Usability ease of use and learning
• These concepts are often in conflict
• An interface that is easy to learn is not always
  easy to use
• Eg. Menu-based applications with multiple forms
  and dialog boxes etc. are easy to learn
• Easy to learn interfaces are appropriate for
  systems used infrequently
• But if system used all day by office-workers
  important to make interface fast and flexible
  with shortcuts, hot keys and information-intensive
  screens (may be harder to learn but easier to
  use once learned)

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Testing for Usability

• Developers use many techniques to evaluate
  interface designs to ensure usability
• Some methods
• Formal surveys
• Focus group meetings
• Design walkthroughs
• Paper and pencil evaluations
• Expert evaluations
• Formal laboratory experiments
• Informal observation
• Some methods allow collection of objective data
  that can be analyzed statistically

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Example video-based usability testing

• Method Im using video record subjects
  (representative users of systems, e.g. doctors,
  nurses) as they interact with a system and
  think-aloud
• Record all screens on video
• Can code the video to identify problems users
  have and suggestions for improvement
• Can statistically compare alternative designs
• Can provide feedback to designers to improve
  design

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Usability continued

• Third principle of user-centered design
• Use iterative development doing some analysis,
  then some design then some implementation (and
  repeat)
• cycling through with some analysis (evaluation of
  the design) then some feedback to designers and
  improvements, followed by further evaluation etc.
• After each iteration the project team evaluates
  the work on the system and makes changes if
  needed
• Iterative development keeps the focus on the user
  by continually refining the system after each
  iteration

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Human-Computer Interaction as a Field of Study

• User-interface design techniques and HCI as a
  field of study evolved from studies of human
  interaction with machines in general human
  factors engineering or ergonomics
• Formal study of human factors began in World War
  II, when aerospace engineers studied the effects
  of arranging controls in cockpit
• What the pilot does is the human factor that
  engineers realized was beyond their control

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• Example of the importance of the human factor
  involving a minor change
• Designers switched location of the throttle and
  the release handle for the ejection seat
• The result was a dramatic increase in the number
  of unexplained pilot ejections!
• When under pressure, the pilots grabbed what they
  thought was the throttle and ejected from the
  plane
• Designers dismissed the problem as need for
  better traning
• But problem continued!
• Became apparent that the key to the human
  factor was to change the machine to accommodate
  the human rather then trying to change the human
  to accommodate the machine
• Computer example in avionics early Airbus
  accidents
• Too much control taken over by the computer system

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Emergence of the field of Human-Computer
Interaction

• The field of human factors was associated with
  engineering, since engineers designed machines
• But engineers often found human factors
  frustrating (different personality types)
• Gradually specialists emerged who drew on many
  disciplines to understand people and their
  behavior
• Disciplines drawn on for HCI
• Cognitive psychology
• Computer science
• Social psychology
• Linguistics
• Sociology
• anthropology

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Example Impact of HCI work from Xerox PARC on
computers

• In the 1970s an important contribution to the
  field of HCI began at Xerox Corporation
• Xerox produced high-speed photocopy machines with
  ever increasing options
• Recognized the importance of making these
  machines easy to use and learn
• Xerox hired people with many backgrounds e.g.
  computers, psychology, anthropology etc.
• Xerox started the Xerox Palo Alto Research Centre
  (Xerox PARC) to study issues that affect how
  humans operate machines

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• Xerox began offering photocopy machines with
• Touch screens
• Menu-driven interfaces displaying icons like
  stacks of paper, staples etc.
• Research at Xerox PARC also included work on
  computers
• First object-oriented language, Smalltalk was
  developed by Alan Kay at PARC
• First laser printer
• Basis of portable computing worked out at PARC as
  well
• Kay developed a portable personal computing
  platform (Dynabook)
• Key aspects of GUI (graphical user interfaces)
  also worked out at Xerox PARC

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• In late 70s Xerox developed the first
  general-purpose personal computer with a
  graphical user interface the Xerox Star
• Although it was ahead of its time and too
  expensive it is a landmark in computing
• Key features of it were exploited in the early
  1980s by Apple Computers (which was located
  physically next to Xerox PARC in Silicon Valley)
• The features from the Star became part of the
  Apple Lisa, which led to the Apple Macintosh
• The story doesnt end there! the Microsoft
  Windows graphical user interface essentially
  evolved from the Apple Macintosh interface
  (initially was a legal battle between Apple and
  Microsoft over the rights)

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Field of Human-Computer Interaction (HCI)

• The field of HCI has evolved
• Academic programs in it (through Computer Science
  and Psychology programs and departments)
• Undergraduate and graduate programs
• Major conferences, journals and books
• In industry it is beginning to have a major
  impact
• Usability laboratories
• Eg. Hewlitt-Packard, Microsoft, Apple, American
  Airlines etc.
• Hire multidisciplinary staff
• Computer scientists
• Psychologists
• Graphics designers
• Ethnographers

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Metaphors for Human-Computer Interaction

• The term metaphor describes the overall concept
  you may use to organize all the objects and
  actions in an interface into a coherent whole
• Three major metaphors, or analogies in HCI
• Direct manipulation metaphor
• Desktop metaphor
• Document metaphor
• Direct manipulation metaphor
• A metaphor of HCI in which the user interacts
  directly with objects on the display screen
• Objects are made visible so the user can point at
  them and manipulate them with the mouse or arrow
  keys
• Earliest direct manipulation interfaces were word
  processors that let users type in words directly
  into a document in a spreadsheet (which on the
  screen was conceptually similar to a paper
  spreadsheet)

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Direct Manipulation Metaphor (cont.)

• Early direct manipulation applications that run
  using DOS (e.g. spreadsheets, word processors)
  led to popularity of personal computers
• Smalltalk language developed at Xerox PARC
  extended direct manipulation to all objects on
  the screen
• Buttons
• Check boxes
• Scroll bars
• Slider controls
• New icons appeared eg. Trash cans, which
  allowed you to directly manipulate an object
  put it in the trash

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Desktop Metaphor

• Direct manipulation coupled with object-oriented
  programming eventually evolved into the desktop
  metaphor
• The display screen includes an arrangement of
  common desktop objects
• Notepad, a calendar, a calculator, file folders
  containing documents
• Newer ones also include a telephone, an answering
  machine, a CD player
• Interacting with these objects is similar to
  interacting with real-world objects they represent

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